Taking the fundamental and comprehensive reform of EU competition policy which embodies a shift from a formalistic regulatory approach towards a more economic approach as a point of departure, this article argues that it is time for antitrust policy to move beyond structural understandings of competition ("preserving competition") and into the realm of explicit welfare analysis. A "more economic approach" should reflect current economic thinking about competition, incentives and efficiency. Competition is defined in the paper as a process of creating and appropriating value (social surplus). Allocative, technical and innovative inefficiencies are viewed as fundamentally due to failures of capturing value. The paper argues that antitrust laws should recognize a defence for all private acts that restrain ?competition? under the traditional antitrust analysis but advance total welfare. The proposed efficiency defence is, however, limited to intramarket second-best tradeoffs, i.e. tradeoffs involving market failures in the relevant market. To rebut a finding of illegality based upon a traditional presumption of anticompetitive effects, defendants should have to establish, first, that the challenged conduct is responsive to an identifiable market failure, broadly defined as allocative, technical or innovative inefficiency in the relevant market; second, that the conduct produces a net increase in total welfare ("intramarket second-best claim"). The antitrust authorities should accept the defence if, first, the conduct will not substantially impair the ability of public or private actors subsequently to ameliorate the effects of the market failure; and if, second, there is no less restrictive alternative consistent with the antitrust laws that could achieve similar welfare gains. The paper also assesses the costs and benefits of implementing an intra-market second-best defence and argues that this approach provides better criteria for a workable antitrust policy than an antitrust standard based on protecting "competition".